Hello Everyone, I have a 1964 Buick Riviera (401) with some upgrades. I recently had a cam (w/ new springs, lifters), and a TA 25 torque converter installed. I am considering, putting new gears in, but not sure what ratio would be a good match for my set up without hacking or tampering with the rear end too much. I would like a more responsive launch off the line because right now it does not have any low end at all. Any advice or help would be greatly appreciated! Thank you for your time.
You are going to get 100 responses here and the best advice I can give you is to call JEGS and speak to a tech, It will take 5 minutes and they will ask you what you have now and what you are looking to get out of your car and give you the best options that match exactly what setup you have
JEGS has no tech that knows squat about this. You will have to post in Parts Wanted for a used set of gears. At this time no one makes Buick 9 3/8s.
I have a 3.42 Riviera differential for sale. Going @ $650. Plus shipping from Cincinnati to wherever you are
One of the easiest things you could do to help your dead stop acceleration would be to have a 2.75:1 first gear set installed into your T400 trans. Not sure who sells this gear set today but it will make a difference. 3.00:1 are even better but I'm not sure if anyone is still making them.
A bigger cam will reduce low end power, but increase top-end power. That's just how it is. Your '64 trans doesn't have the switch-pitch converter, so a higher stall one will get the engine more into the power band. Modifying the distributor for a quicker mechanical advance as well as more initial advance will likely boost off the line performance, I'd suggest starting there. Either find a 2x4 or a Dynaflow distributor or have yours modified. Shorter rear tires will have the same effect as increasing the gears. What size tires do you have?
I've used a 2.75 gearset for decades, it worked great with my 2.56 rearend and switch-pitch. I used to have a 3.00:1 gearset, however I managed to break that. Most people will probably not have the same problem I did - I was using a pretty big nitrous shot on top of an already healthy 455. I have beat the crap out of the 2.75 gearset, and never had any issues. There is a noticable difference in "stoplight response" when using the 3.00 gearset, for sure. The difference is also there with 2.75:1, although obviously not quite the same. -Bob C.
Thank you Mike for the info. I'm hoping to find 3.42's, but like you said not sure if anyone is reproducing them. Also, if I have the factory 3.07, will my axles need to be changed if converted to 3.42?
Thanks Bob for the input! Much appreciated. Yeah I think I'm leaning toward the 3.00:1 gear set for freeway use/ drivability as well. I hope I will be able to make the conversion!
One of my cars is a 67 GS California, 340 with 110 cam. I kept the 2.78:1 rear end. Tried the switch pitch ST300 with modified convertor and it was OK, then replaced it with a TH350 that has a low gear first and a higher stall convertor. Man is that a great combination.